The invention comprises a framework for efficiently generating and controlling forecasts from historical data, and arose in financial forecasting originally. With the advent of personal computers, a number of forecasting packages have been introduced. A typical accountancy package will provide for sequential entry of historical accountancy data, and a computing "engine" will process this data to provide accountancy output, which is compared with a budget. The "engine" will generally be invisible to the user, and its operation need not be understood by the user. In fact, it is commonly the case that the user will not be able to determine how the "engine" is processing the accountancy data to produce the output. Some systems, in an endeavour to reduce the ability of users to tamper with the input data, restrict users ability to change data once entered. These packages tend to be inflexible in their provision of reports, do not usually provide any forecasting facilities, and do not have provision to include technical non-accounting data. Other packages concentrate on forecasting, with minimal or no historical data. Yet other spreadsheet systems are developed to forecast results for companies for economic investment appraisals, but do not include basic accounting controls such as double-entry bookkeeping, applied to forecasts.